1. Field of the Invention
The present invention relates to a film-forming apparatus, and specifically to a technique for preventing contamination in a multi-target sputter film-forming apparatus that includes a plurality of target electrodes made of different materials in a single chamber, for example, and that forms a multi-layered film by sputtering, using a rotary shutter apparatus.
2. Description of the Related Art
A multi-target sputter film-forming apparatus (for example, Japanese Patent Laid-Open No. 2011-001597) can form a required multi-layered film in a single film-forming chamber by sputtering continuously without interruption from the bottom layer to the top layer on a substrate.
In order to form a multi-layered film by sputtering, in the film-forming apparatus disclosed in Japanese Patent Laid-Open No. 2011-001597, in a single chamber, a plurality of targets made of different materials are disposed on a ceiling portion of the substrate on which a film is to be formed, and a shutter apparatus for selecting a target to be used in sputter film formation is also provided. The shutter apparatus has a double shutter structure including shutter plates that rotate independently of each other. Each of the two shutter plates has a required number of openings formed in predetermined positions so that a selected target can be viewed from the substrate side.
With the rotary shutter apparatus, targets made of materials not to be used in film formation are shielded, and targets made of materials to be used in sputter film formation become visible from a substrate through the openings. The rotary shutter apparatus includes two shutter plates having a substantially circular shape as viewed from the substrate, and the two shutter plates are configured to rotate independently of each other. To select a target to be used in sputter film formation, each shutter plate is rotated by the rotary shutter apparatus such that a target made of a material that needs to be used in film formation faces the substrate through the opening.
In the case of sputter film formation in which a plurality of targets made of different material to be used in film formation are selected in a specific order, if contamination occurs between the targets, the performance of the formed film may be low. There is a need for a technique for reliably preventing the occurrence of contamination in order to deposit a high-performance multi-layered film on a substrate.